Brother has not released printer drivers for the Raspberry Pi's ARM architecture for its range of inkjets, and the i386 drivers apparently don;t work. There are CUPS drivers for many Brother laser printers, but not for the inkjets. That leaves those of us with a Brother stuck with turning on a network printer that is connected to a Brother printer and using that.
But there's another way. For years I have been using Brother's "iPrint & Scan' app on Android to print to any of the three Brother inkjets on my network.
However there are times when the computers are turned off and I can't be bothered turning one on just to print a file, then shutting down again. But I almost always have a phone or table turned on. So I have iPrint& Scan installed on my Android devices.
This works with the Raspberry Pi 3B with built in Bluetooth and I suppose it would work with an earlier Pi that has a Bluetooth dongle.
First, I set up my Brother MFC-J6510DW printers using the WPS option and the button on my router. Takes a few seconds to automatically become available in the WLAN.
Next I activated bluetooth on my Samsung Galaxy Tab 2 10.1.
Then I opened the Bluetooth GUI on the Pi 3 and searched. It found the Tablet, so I sent a file via bluetooth. An Accept? option poppeed up on the Tablet, and tapping Yes, the file transferred.
So far, so good. I opened the Brother iPrint and Scan app, and it found the printer and connected, then I just had to select the file I transferred from the Raspberry Pi and it showed it in Print Preview, and allowed me to change some settings if I wished.
I chose Print, and out it came.
Certainly not an elegant solution, and it does require wireless access to the network, but it works and solves one problem for me. It might make life easier for anyone else with an Android or Apple device and a Brother Inkjet.